Known as a conventional spectroscopic sensor is one comprising an interference filter unit for transmitting therethrough light having a predetermined wavelength according to an incident position of light, a light-transmitting substrate for transmitting therethrough the light incident on the interference filter unit, and a light-detecting substrate for detecting the light transmitted through the interference filter unit. Here, a pair of mirror layers may oppose each other through a cavity layer so as to construct the interference filter unit as that of Fabry-Perot type.
As a method for manufacturing such a spectroscopic sensor, the following method is disclosed in Patent Literature 1. First, one mirror layer is formed on a light-detecting substrate, and then a cavity layer is formed by a nanoimprint process on the mirror layer. Subsequently, the other mirror layer is formed on the cavity layer, and finally a light-transmitting substrate is joined onto the latter mirror layer.